Tap holder



y 3, 1932- M H. CORLEY I 1,857,012

I TAP HOLDER Filed March 15, 1931 I @ii,

Patented May 3, 1932 UNITED STATES PATENT OFFICE MARK H. CORLEY, OF CHICAGO, ILLINOIS, ASSIGNOR TO PROCUNIER SAFETYCHUCK COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS TA]? HOLDER Application .filed March 13, 1931. Serial No. 522,252.;

This invention is an improvement on the patent to William L. Procunier,N0. 1,117,241, granted November 17, 1914.

An object of this invention is to provide a tap holder in which the operator can see the L tap and while 1t is being gripped thereby,

and a further object is to provide an 1m-' proved form of gripping jaw.

These and other objects, as will hereinafter appear, are accomplished by this invention which is fully described in the following specification and shown in the accompanying drawings, in which- Figure 1 is a view in elevation of the tap I holder with a tap held in place;

Fig. 2 is a vertical sectional view taken as indicated on the line 22 of Fig. 3;

Fig. 3 is a transverse section of Fig. 2 taken as indicated by the line 3-3 of Fig. 2;

Fi 4 is a bottom plan view of the bod showing the tapered cavity therein;

Fig. 5 is a view in elevation of one of the gripping jaws showing the inner face thereof;

Fig. 6 is a view'similar to Fig. 5 showing the outer surface of the gripping jaws;

Fig. 7 is a plan view of a gripping jaw; and

Fig. 8 is a sectional view of the gripping jaw taken as indicated by the line 8-8 of Flg. 5.

The embodiment illustrated comprises a tap holder having a body 10 provided at its upper end with a tapped axial opening 11 by which the tap holder may be secured to a threaded end of a driving shaft (not shown). The tapped opening terminates in a tapered cavity 12 which opens outwardly, the body being provided with slots 13 and 14 opening into the tapered cavity, the purpose of which will presently be described. The outer surface of the body is threaded to receive an internally threaded shell 16 which consists of a tubular portion 17 having 5 openings 18 formed therein, and terminating at one end to form an internal tapered cavity 19. The openings'lS in the shell register with the slots 14 in the body'to permit a view of the space within the shell which contains a pair of spaced gripping jaws 20 and 21 for" gripping and centering a tap 22 having flats 23 formed at one end thereof.

Each of the gripping jaws are alike, and consists of a gripping piece 25 and a centering piece 26, the gripping piece having a base 27 and an outer surface 28 tapering away from the base atan angle to fit the cavity 12. The tapered surface may be out on different planes to provide bearing edges 29. The gripping piece may have an inner face 30, which is highly polished to reflect light which enters the openings in the shell and body, the edges of the face being rounded as at 31 to freely admit the light to the center of the gripping aws. The gripping piece is provided with a longitudinal V-shaped groove 32 for receiving the flats of a tap, the groove being beveled at 33 to facilitate the entrance of a tap end therein;

The centering piece 26 forming the lower part of the gripping jaw may be substantially one-half of a frustum of a cone, the base of which fits against the base 27 of the gripping piece, and is pivotally held thereagainst by a pin 35 having a split ring 36 fitted in a groove in a well known manner so that the two pieces, when assembled, are inseparable. To limit the pivoting movement of the pieces relative to each other, the cen tering piece may be provided with a tongue 37 which extends into an opening 38 in the gripping piece. The tapered outer surface of the centering piece may be cut on a plane to provide bearing edges 39 similar to the bearing edges 29 on the gripping piece. The inner face 40 is provided with a concave groove 41 in axial alignment with the center line of the piece, the groove being threaded or roughened to assist in holding the shank of the tap, and beveled at its outer end, as at 42, to facilitate the entryof a tap end.

The outer ends of the gripping jaws 25 may be provided with openings 45, countersunk tween the gripping jaws and surrounding the pin 47, the ends of the spring being received in (the countersinks 46, the spring tending to separate the gripping jaws. This is particularly advantageous when the chuck is secured to a horizontal shaft where the jaws would tend to lie in contact with each other.

To fit a tap within the present holder the shell is screwed to a position so that the gripping jaws are separated far enough to admit insertion of the tap end which is facili tated by'the beveled edges 42 and 43. With the arrangement of the openingsls and the slots 14, it is possible for the operator to see.

the tap end, as shown in Fig. 1, so that he is sure the tap is properly fitted between the jaws. Heretofore it was a frequent occurrehce for the operatgr'to insert the tap end between the jaws where it abutted against the base of the gripping piece and was secured in such a position whereby the centering piece gripped the faces of the tap. With a tap secured in this manner when applied to work, the centering aws were put under undue strain often breaking them and some times breaking the shell. After the operator has the tap end properly placed between the jaws, the shell is screwed upon the body,

, whereupon the tapered cavities by contact- ;ing with the bearing edges 29 and 39 force the gripping aws together, the centering pieces contacting the neck ofthe tap and the gripping pieces contacting the faces on the tap end. i

t will be seen that when a small tap is secured in the chuck, the shell will be screwed further onto the body than when a large tap 7 is secured therein; similarly the gripping jaws are located further into the tapered cavities. In all operative positions, however, the operator has a clear view of the tap end. It will be noted that in Fig. 3 the openings 18 may, in addition to permitting V a view of the tap, be used for engaging with the tip of a spanner wrench for final tightening 'of the shell.

, While I have shown and described but a single embodiment of my invention, it will be understood that it is capable ofmany modifications. Changes, therefore, in the construction and arrangement may be made which do not depart from the spirit and scope of the invention as disclosed in the appended claims.

I claim p 1. A tap holder comprising a body having a tapered cavity in one end and transverse slots cutting through the, cavity, a shell adapted to screw onto the slotted end of the body, the shell having a tubular portion terminating at one end to form an internally tapered cavity, said she'll having openings in the tubular-portion, spaced tap gripping jaws engaging with the tapered cavities to hold a tap therebetween, cooperating means on the 1 jaws and body for holding the gripping jaws against rotary movement relative to the ta ered cavities, means for movably securing the two pieces of each 'aw together, coacting pin and socket means or limiting the movement of one piece relative to the other, whereby the jaw pieces will operate as a unit yet permit limited movement of one piece relativeto the other in centering theneck of a tap in the holder and means for securing the jaws against rotary movement relative to the" body.

3. A tap holder comprising a body having a tapered cavity in one end, a shell adapted to screw onto said end of the body, the shell having a tubular portion terminating at one end to form an internally tapered cavity, a plurality of jaws having conical ends adapted to fit said tapered cavities, each jaw comprising a tap centering piece and a tap gripping piece, each gripping .piecehaving transverse openings therein, a pin rotatably securing the pieces of each jaw together, one of said pieces being formed with a socket and the other with means projecting into the socket for limitingthe movement of one piece of each jaw relative to the other whereby the jaw pieces will operate :as .a unit yet yield suificiently to center theneck of a tap in the holder, and a pin fitted in the openings in the gripping pieces and engaging the body to prevent rotary movementof the gripping jaws relative to the body.

4. A tapholder comprising a body, a shell in threaded connection therewith, the body and shell each being provided with a conical cavity facing each other, and gripping jaws having their outer surfaces tapering toward their ends, the tapering portions of the jaws relieved to provide one or more flattened areas providing edges coincident with ele ments of the cone to bear against the conical surfaces of the cavities whereby to reduce friction and prevent canting of the jaws when moved toward clamping position. V

5. A tap holder comprising a body having a tapered cavity in one end, .ashell adapted to screw onto said end of the body, the body and shell having re istering openings :and the shell having a tu ular portion terminating at one end to form an internally tapered -cavity, a,plurality of spaced jaws havingconical ends adapted to fit said tapered cavities, each jaw comprising a tap centering piece and a tap gripping piece, each gripping piece jaws apart.

MARK H. CORLEY. 

